Pakistan gave China access to the previously unknown "stealth" helicopter that crashed during the commando raid that killed Osama bin Laden in May despite explicit requests from the CIA not to, the Financial Times reported on Sunday.

The revelation, if confirmed, is likely to further shake the U.S.-Pakistan relationship, which has been improving slightly after hitting its lowest point in decades following the May 2 bin Laden raid. During the raid, one of two modified Blackhawk helicopters, believed to employ unknown stealth.